[PDF] Extraction of high-value added compounds by subcritical water and

View - Download Extraction of high-value added compounds by subcritical water and

Previous PDF

Next PDF

THÈSE PRÉSENTÉE

POUR OBTENIR LE GRADE DE

DOCTEUR DE

L'UNIVERSITÉ DE BORDEAUX ÉCOLE DOCTORALE DES SCIENCES DE LA VIE ET DE LA SANTE

SPÉCIALITÉ : OENOLOGIE

Par Sami YAMMINE

EXTRACTION DES MOLECULES A HAUTE VALEUR

AJOUTEE PAR EAU SOUS CRITIQUE ET

FRACTIONNEMENT PAR PROCEDES

MEMBRANAIRES Valorisation des co-produits de la vigne et du vin par des procédés éco-innovants

Sous la direction de : Martine MIETTON-PEUCHOT

Soutenue le 3 Mai 2016

Membres du jury :

Pr. VACA GARCIA, Carlos Université de Toulouse Président Pr. WISNIEWSKI, Christelle Université de Montpellier Rapporteur Pr. BOUTIN, Olivier Université de Marseille Rapporteur Pr. FERRARI, Giovanna Université de Salerne, ITALIE Examinateur Dr. GHIDOSSI, Rémy Université de Bordeaux Examinateur Pr. MIETTON-PEUCHOT, Martine Université de Bordeaux Directrice Dr. EL RAYES, Youssef Université de USEK, LIBAN Invité

À mes parents, et à Joëlle.

Soyons reconnaissants aux personnes qui nous donnent du bonheur ; elles sont les charmants jardiniers par qui nos âmes sont fleuries. Marcel Proust La plus grande difficulté avec les remerciements, c'est d'essayer de penser à tout le monde. Mais durant ces trois années, il y a tellement de personnes qui m'ont aidées à traverser cette épreuve, que je ne peux pas tous les citer. Et je m'excuse donc par avance pour les noms qui ne sont pas cités. Pour commencer, je tiens à remercier ma directrice de thèse Martine Mietton-Peuchot, sans qui cett e thèse n'aurait pas pu e xister, progresser et aboutir. Je la remercie de m'avoir toujours laissé cette part d'autonomie sur les problèmes que je voulais traiter et ses nombreux conseils, sa profonde humanité, et ses encouragements qui m'ont permis d'avancer dans ce travail! Cette dernière n'aurait pas vu le jour sans la confiance, la patience, et la générosité qu'elle ma su m'accorder. Merci pour tout ! Je remercie également Remy Ghidossi pour l a transmission de ses connaissances et de son enthousiasme, pour son encadrement a u quotidie n et son soutien permanent. Je remercie Christelle Wisniewski et Olivier Boutin qui m'ont fait l'honneur d'être rapporteurs de cette thèse. Merci également à Giovanna Ferrari, Carlos Vaca Garcia, et Youssef el Rayes d'avoir accepté de faire partie de ce j ury en tant qu'examinateur. Je désire remercier les membres de l'équipe Génie des Procédés et Environnement à l'ISVV, au sein de laquelle j'ai effectué cette thèse. Je ne pouvais y espérer un meilleur accueil que celui qui m'a été octroyé. Je tiens à remercier tout particulièrement Caroline et Xavier Vitrac pour leur collaboration sur la partie extraction et analyses de ma thèse et leur aide en général durant ces trois années. Il y a trop de gens à remercier à l'ISVV pour tous les citer, mais certains ont plus compté que d'autres. Je remercie mes maneyik prefés Arnaud et Fabrice de m'avoir souvent donné la possibilité de travailler seul et au calme. À titre plus personnel je rem ercie toute ma famille à c ommencer par m es parents, pour avoir toujours été là, pour m'avoir donné la chance de faire de longues études, pour leur soutien sans limite durant toute ma scolarité et plus particulièrement ces trois dernières années. Merci à mon frère pour son encouragements et pour les bons moment s passés ensemble quand on peut se retrouver, merci à Greg en particulier pour tous ses conseils en rapport à la thèse et la recherche en général. Si j'ai pu faire cette thèse, c'est avant tout grâce aux activités extérieures et aux amis qui sont toujours là. Et enfin merci à Joelle, je ne saurai jamais assez la remercier de ce qu'elle a fait pour moi. Cette thèse n'aurait pas pu se finir dans les temps si elle n'avait pas été là. C'est amusant que ce soit la personne la plus loin géographiquement de moi qui est été la plus proche durant ces six derniers mois, merci à elle pour m'avoir encouragé, changé les idées, forcé à me bouger pour ne penser qu'à ma thèse. Merci pour tout.

Abstract This work has dealt with extraction of natural substances from winery by-products using "green" processes such as extraction by subcritical water and purification by membrane processes. Thes e processes are an alternative to solvent extract ion traditionally used in the natural products industry. Main part of the work was done on different grape pomace, extraction was optimized and compared in terms of yield, chemical composition, and antioxidant activity of extracts. D unkel felder extracts exhibited the strongest antioxidant activity and comparison of chemical compositions of the different extracts indicated. Furthermore this Dunkelfelder grape pomace was used as model in order to optimiz e the different process parameters such as temperature, pressure and hydraulic retention t ime. After the subcritic al water extraction, extracts produced were found to be rich in several families of molecules. An esse ntial purification step of target compounds prior to industrial use was indispensable. Coupling the subcritical water with membrane processes offers an innovative solution for the purification of these extracts. Thereby, the extract was assayed in a cross-flow apparatus against eleven membranes of ultrafiltration (100 to 2 kDa) and nine membranes of nanofiltration (1000 to 150 Da). The monitoring of the process was carried out by determ ining performance parameter s and ret ention coefficients of different families of macro and micromolecules. The results obtained have demonstrat ed that the use of membrane technol ogies could bring i nnovative changes in the recovery of bioactive compounds for future industries. Keywords: Subcritical water extraction, membrane fractionation, phenolic compounds, grape pomace.

Résumé Ce travail a porté sur l'extraction de substances naturelles de sous-produits de la vigne en mettant en oeuvre des procédés "verts" tels que l'extraction par eau sous-critique et la purification par filtration membranaire. Ces procédés représentent une alternative à l'extraction par solvant, traditionnellement utilisée dans la production de substances bio-sourcés. La majeure partie de cette étude a été menée sur des marcs de raisin de cépages variés, l'extraction a été optimisée et comparée sur la base du re ndement, de la composition chimique et de l'activité antioxydante des extraits obtenus. De tous les cépages testés, les extraits de Dunkelfelder ont présenté l'activité antioxydante la plus élevée et la concentration en familles de molé cules polyphénoliques la plus importante. En outre, ce marc de raisin de Dunkelfelder a été utilisé comme modèle afin d'optimis er les différents paramètres du pr océdé tels que la température, la pression et le temps de séjour hydraulique. Après la phase d'extraction par eau sous-critique, les extraits obtenus se sont révélés riches en de nombreuses familles de molécules. Ainsi, une étape de purification des composés cibles avant usage industriel s'est révélée indispensable. Le couplage de l'extraction par eau sous-critique avec des procédés membranaires représente une solution innov ante pour la purificati on de ces extrai ts. Des essais de filtration tangentielle de l'extrait ont été menés avec onze membranes d'ultrafiltration (100 kDa à 2 kDa) et neuf membranes de nanofiltration (1000 Da à 150 Da). Le suivi du procédé s'est appuyé sur une détermination des paramètres opératoires optimisés et sur la détermination des coefficients de rétention des différentes familles des macro et micromolécules. Les résultats obtenus ont démontré que l'utilisation des technologies membranaires pourrait dans le futur, constituer une innovation technologique pour la purification des composes bioactifs. Mots clés: Extraction par eau sous-critique, fractionnement par procédés membranaire, composés phénoliques, marc de raisin.

Foreword A biorefinery is an industrial complex, transforming agricultural biomass, forestry and algae into a variet y of bio-based marketable products (ingredients and supplements for human and animal cons umption, biomolecules, agro-materials) and/or bioenergy (biofuels, electricity, heat). The biorefinery aims at the complete valorisation of all plant components. In order to do this, biorefinery requires steps of pretreatment, fractionation / purification and conversion of the raw material for the optimized production of high value products. To be economically viable and fit a sustainable development perspective, biorefinery must satisfy a double imperative: the competitiveness of its production costs and use of products and environmentally friendly processes, without the generation of additional wa ste (mi nimum environmental impact). One example of a biorefinery, is a distillery, that acts as a main pathway for the valorization of by-products recovered from the winemaking process. Grapes (Vitis vinifera L.) are one of the most cultivated fruit crops in the world with an annual production of 58 million tons in 2012 (FAOSTAT 2012). Approximately 80% of crops are used for winemaking. Mainly winemaking generates solid residue after pressing: the grape pomace, rich in alcohol. According to European regulations (EC Regulation 555/2008 of the Commission of 27 June 2008), these "by-products" must be disposed of in an envi ronmentall y friendly manner. For the French winemakers, the state obliges in either: - Composting, methanisation or spre ading the by-products of all or part of their residues on their own lands - Or by delivery of grape pomace generated to a methanisaton facility, composting, or a distillery (décret n° 2014-903 du 18 août 2014, Art. D. 665-34.-I). In France, about 50 distilleries collect wine by-products, in an average of a 50 km radius around their si te, and allow the recovery of about 850 000 tons of grape pomace each year (Institut français de la vigne et du vin, Novembre 2013). Until now, the wine distilleries ensure the role of removing the entire load of polluting grape pomace, on national territory, for quality reasons (limitation of over-pressing of grapes, wine qualit y) and regulations (f ight agains t fraud and guarantee Customs

regulations). However, the Décret n° 2014-903 August 18, 2014 ended obligation to deliver the wine by-products to the distillery, thus threateni ng the supply of raw material to distilleries. Competitiveness and profitability of the distillery industry is based, therefore, on im proving and modernizing processes. The mai n pedal for improvement is the extraction and purification of high added value compounds from the byproducts. The sector has therefore every interest to move towards an approach of type "biorefinery" maximizing the ways of use of by-products. At the distilleries, pomace is transformed into various by-products (Figure 1) of more or less high added value (alcohol, grape seed oil, fertilizer, lime tartrate, pulp, etc.). These by-products are utiliz ed as raw mat erials in di fferent sectors (agriculture , viticulture, chemical, cosmetic & food industries). This process allows a valorization of the material (compost, feed, chemical ...) and / or energy (bioethanol, biogas...) byproducts. Due to present industrial equipment, distill ation and tartaric acid extraction are currently selected as main me thod of valorizati on in the distillery. However, extraction of phenolic compounds can be integrated into the process of valorization. It would allow a diversification of the distillery activities through the integration of a further step, fra ctionation of the ve getable biomass to extract high added va lue compounds. The markets for such products are numerous: the wine, the food (Dyes, natural preservatives), health (food supplem ents, medicines), cosmetics (nat ural antioxidants) or the chemical industry (green glue adhesive). However, to compete in the production of the plant extracts industry (i.e. Naturex, BERKEM, CHR Hansen, DIANA Ingredients, Oenofrance ...), the distillery has to propose extracts with a particular phenolic composition , thus opening up spe cific markets. Undeniably, the pote ntial application of a plant extract is essentially determined by phytochemical composition, which are particularly dependent on the raw material used and the method of manufacture of the plant extract. It is in this context overall recovery of bio-compounds and minimizing environmental impacts that is part of the research project VALUXTRACT. The overall objective of VALUXTRACT project is the recovery of high added value compounds from solid waste from winemaking industry with "green" methods. In order produce extracts for oenological applications mainly, but also for the food, cosmetics and pharmaceuticals industries. * * *

This PhD thesis was done w ithin the framework of the European project "Valuxtract", financed by the French National Research Agency (ANR) under the 1st transnational Call of ECO-INNOVERA (ERA-NET, ANR-12-INOV- 0001-04). It has been conducted at Unité de Recherche OEnologie located in the Institut de Science de la Vigne et du Vin, Villena ve d'Ornon in Franc e. It was conducted under the supervision of Professor Martine Mietton-Peuchot. Part of this work was done in close collaboration with university of Changins - Haute Ecole de viti culture et oenologie, university Hochschule GEISEN HEIM - Institut für Oenologie, University of Compiègne - Laboratoire Transformations Intégrées de la Matière Renouvelable and Laboratoire Phenobio - Martillac partners of the project. The manuscri pt consists of five publications organize d into three cha pters, (submitted by the time of writing) that reflect the fruit of the results obtained: Chapter one presents an overview on extraction and purification of high added value compounds from by-products of the winemaking chain using alternative/non-conventional processes/technologies. Chapter two is composed of two publications related to the optimization of the extraction of high added value compounds from grape pomace by utilizing subcritical water. The first publication presented the results of the comparative study of the yield of subcritical water extraction of phenolic compounds using multiple raw materials. The second publication describes the optimization of the extraction process grape pomace by subcritical water. The main results of the optimization and the selectivity of this process are described thoroughly. Chapter three compil es two publicat ions that deal with the fractionation and concentration of high added value compounds from extracts by membrane processes. The chapter will focus on the study of ultrafiltration for the fractionation of the extract obtained in order to separate macrom olecules to obtain extract rich in phenolic compounds. The last publication will focus on the utilization of nanofiltration for the fractionation of different families of phenolic compounds.

Table of content Table of content 1. CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION OF HIGH ADDED VALUE COMPOUNDS FROM GRAPE BYPRODUCTS .......................................................................................... 1 1.1. INTRODUCTION ............................................................................................................ 1 1.2. EXTRACTION AND PURIFICATION OF HIGH ADDED VALUE COMPOUNDS FROM BY-PRODUCTS OF THE WINEMAKING CHAIN USING ALTERNATIVE/NON-CONVENTIONAL PROCESSES/TECHNOLOGIES .................................................................................................... 2 1.2.1. Introduction .......................................................................................................... 3 1.2.2. Pre-treatment of grape by-products for the enhancement of mass transfer phenomena: conventional and alternative techniques ....................................................... 5 1.2.2.1. Grinding ..................................................................................................................................... 5 1.2.2.2. Pulsed electrical field (PEF) assisted extraction ........................................................................ 6 1.2.2.3. High voltage electrical discharges (HVED) assisted extraction .............................................. 10 1.2.2.4. Ultrasound (US) assisted extraction ........................................................................................ 13 1.2.2.5. Comparison of pre-treatment processes ................................................................................... 18 1.2.3. Solid-to-Liquid extraction (SLE) of high added value compounds .................... 20 1.2.3.1. Conventional extraction technique: Low pressure extraction using organic solvents ............. 20 1.2.3.2. High-pressure extraction .......................................................................................................... 23 1.2.3.2.1. High temperature and high-pressure extraction/ Subcritical water extraction (SWE) .... 23 1.2.3.2.2. Supercritical fluid extraction (SFE) ................................................................................ 26 1.2.3.3. Comparison of extraction processes ........................................................................................ 29 1.2.4. Purification and fractionation of the extract ...................................................... 30 1.2.4.1. Solid phase extraction .............................................................................................................. 30 1.2.4.2. Resin adsorption ...................................................................................................................... 31 1.2.4.3. Membrane processes ................................................................................................................ 31 1.2.5. Conclusion .......................................................................................................... 32 References ........................................................................................................................ 34 CHAPTER CONCLUSION AND OBJECTIVES OF THE PROJECT .................................................. 40 2. CHAPTER 2: SUBCRITICAL WATER EXTRACTION OF HIGH ADDED VALUE COMPOUNDS FROM FERMENTED GRAPE POMACE ............................... 42 2.1. INTRODUCTION .......................................................................................................... 42 2.2. CHARACTERIZATION OF POLYPHENOLS AND ANTIOXIDANT POTENTIAL OF RED AND WHITE POMACE BY-PRODUCT EXTRACTS USING SUBCRITICAL WATER EXTRACTION .......... 44 2.2.1. Introduction ........................................................................................................ 46 2.2.2. Material and methods ......................................................................................... 49 2.2.2.1. Chemicals ................................................................................................................................ 49 2.2.2.2. Raw material ............................................................................................................................ 49 2.2.2.3. Process of extraction and parameters ...................................................................................... 50 2.2.2.4. Conventional extraction experiments ...................................................................................... 52 2.2.2.5. Analysis ................................................................................................................................... 52 2.2.2.5.1. Total polyphenols content ............................................................................................... 52 2.2.2.5.2. Antioxidant activity ......................................................................................................... 52 2.2.2.5.2.1. ABTS Assay ................................................................................................................. 53 2.2.2.5.2.2. CUPRAC Assay ........................................................................................................... 54 2.2.2.5.2.3. FRAP Assay ................................................................................................................. 54 2.2.2.5.2.4. ORAC Assay ................................................................................................................ 54 2.2.2.5.3. Anthocyanins analyses .................................................................................................... 55 2.2.2.5.4. Flavan-3-ols and gallic acid analyses .............................................................................. 55 2.2.2.6. Statistics ................................................................................................................................... 56 2.2.3. Results and discussion ........................................................................................ 56 2.2.3.1. Total Polyphenol Content. ....................................................................................................... 56 2.2.3.2. Total Proanthocyanidins Content ............................................................................................ 59 2.2.3.3. HPLC Analysis of Monomeric and Oligomeric Flavan-3-ols ................................................. 60 2.2.3.4. HPLC Analysis of Anthocyanins for red grape by-products ................................................... 61 2.2.3.5. Antioxidant Capacity ............................................................................................................... 64 2.2.4. Conclusion .......................................................................................................... 69 References ........................................................................................................................ 70

Table of content 2.3. SUBCRITICAL WATER EXTRACTION AND NEOFORMATION OF ANTIOXIDANT COMPOUNDS FROM DUNKELFELDER GRAPE POMACE .......................................................... 74 2.3.1. Introduction ........................................................................................................ 76 2.3.2. Material and methods ......................................................................................... 78 2.3.2.1. Raw material ............................................................................................................................ 78 2.3.2.2. Process of extraction and parameters ...................................................................................... 78 2.3.2.3. Conventional extraction experiments ...................................................................................... 80 2.3.2.4. Analysis ................................................................................................................................... 80 2.3.2.4.1. Total polyphenols content ............................................................................................... 80 2.3.2.4.2. Antioxidant activity ......................................................................................................... 81 2.3.2.4.3. Anthocyanins analyses .................................................................................................... 81 2.3.2.4.4. Flavan-3-ols and gallic acid analyses .............................................................................. 82 2.3.2.4.5. Analysis of Hydroxymethylfurfural (HMF) and Furfural ............................................... 83 2.3.2.5. Statistics ................................................................................................................................... 83 2.3.3. Results and discussion ........................................................................................ 83 2.3.3.1. Influence of operating parameters ........................................................................................... 83 2.3.3.2. Temperature ............................................................................................................................. 84 2.3.3.3. Pressure .................................................................................................................................... 85 2.3.3.4. Flow rate/hydraulic retention time ........................................................................................... 85 2.3.3.5. Temperature influence on the extract composition .................................................................. 86 2.3.3.6. Antioxidant Capacity of the Extracts ....................................................................................... 89 2.3.3.7. Maillard and Caramelization Reactions ................................................................................... 90 2.3.4. Conclusions ......................................................................................................... 91 References ........................................................................................................................ 93 CHAPTER CONCLUSION ........................................................................................................ 96 3. CHAPTER 3: FRACTIONATION OF DIFFERENT PHENOLIC CLASSES FROM GRAPE POMACE EXTRACTS BY MEMBRANE PROCESSES ..................... 97 3.1. INTRODUCTION .......................................................................................................... 97 3.2. SELECTING ULTRAFILTRATION MEMBRANES TO FRACTIONING HIGH ADDED VALUE COMPOUNDS FROM GRAPE POMACE EXTRACTS ................................................................... 98 3.2.1. Introduction ...................................................................................................... 100 3.2.2. Materials and methods ..................................................................................... 102 3.2.2.1. Subcritical water extraction ................................................................................................... 102 3.2.2.2. Experimental analysis and membranes .................................................................................. 103 3.2.2.3. Membrane performance ......................................................................................................... 103 3.2.2.4. Hydraulic resistance, using Darcy's law ................................................................................ 105 3.2.2.5. Contact angle ......................................................................................................................... 106 3.2.2.6. Chemical analysis .................................................................................................................. 106 3.2.2.6.1. pH, Total sugars, Polysaccharrides ............................................................................... 106 3.2.2.6.2. Proteins .......................................................................................................................... 106 3.2.2.6.3. Total polyphenols content ............................................................................................. 107 3.2.2.6.4. Antioxidant activity - ORAC ........................................................................................ 107 3.2.2.6.5. Phenolic classes ............................................................................................................. 107 3.2.3. Results and discussion ...................................................................................... 108 3.2.3.1. Grape subcritical extract composition ................................................................................... 108 3.2.3.2. Membrane performance ......................................................................................................... 109 3.2.3.2.1.1. Water permeability determination .............................................................................. 109 3.2.3.2.1.2. Influence of operating conditions on the permeate flux ............................................. 111 3.2.3.2.2. Retention of compounds ................................................................................................ 113 3.2.4. Discussion ......................................................................................................... 116 3.2.4.1. Retention of macromolecules ................................................................................................ 116 3.2.4.1.1. Retention of polysaccharides ......................................................................................... 116 3.2.4.1.2. Retention of proteins ..................................................................................................... 118 3.2.4.1.3. Retention and fractioning of polyphenols ..................................................................... 119 3.2.5. Conclusion ........................................................................................................ 122 References ...................................................................................................................... 123 3.3. THE USE OF NANOFILTRATION MEMBRANES FOR THE FRACTIONATION OF POLYPHENOLS FROM GRAPE POMACE EXTRACT ................................................................ 129 3.3.1. Introduction ...................................................................................................... 131 3.3.2. Materials and methods ..................................................................................... 133 3.3.2.1. Experimental equipment and membranes .............................................................................. 133

Table of content 3.3.2.2. Subcritical water extraction ................................................................................................... 134 3.3.2.3. Filtration experiments ............................................................................................................ 135 3.3.2.4. Analytical methods ................................................................................................................ 136 3.3.2.4.1. Contact angle ................................................................................................................. 136 3.3.2.4.2. pH and Total sugars ....................................................................................................... 137 3.3.2.4.3. Total polyphenols content ............................................................................................. 137 3.3.2.4.4. Antioxidant activity - ORAC ........................................................................................ 137 3.3.2.4.5. Phenolic classes: ............................................................................................................ 138 3.3.3. Results and discussion ...................................................................................... 139 3.3.3.1. Water permeability determination ......................................................................................... 139 3.3.3.2. Influence of operating conditions on the permeate flux ........................................................ 140 3.3.3.3. Fouling resistance .................................................................................................................. 146 3.3.3.4. Phenolic compounds fractionation ........................................................................................ 148 3.3.4. Conclusion ........................................................................................................ 153 References ...................................................................................................................... 154 CHAPTER CONCLUSION ............................................................................................... 157 GENERAL CONCLUSION ................................................................................................ 158 RESUME GENERAL .......................................................................................................... 161 CHAPITRE 1: ETAT DE L'ART .............................................................................................. 165 ENJEUX ET CONSIDERATIONS ............................................................................................. 168 CHAPITRE 2 EXTRACTION PAR EAU SOUS-CRITIQUE DE COMPOSES A HAUTE VALEUR AJOUTEE A PARTIR DE MARC DE RAISIN ............................................................................. 170 CHAPITRE 3: FRACTIONNEMENT DES DIFFERENTES FAMILLES DE MOLECULES PHENOLIQUES A PARTIR D'EXTRAITS DE MARC PAR DES PROCEDES MEMBRANAIRES. ...... 174 CONCLUSION GÉNÉRALE ............................................................................................ 177

List of Figures List of Figures : Chapter 1 : Extraction and purification of high added value compounds from by-products of the winemaking chain using alternative/non-conventional processes/technologies. Figure 1 Conventional extraction procedure for the recovery of high added value components from grape wastes .............................................................................. 4Figure 2 Comparison of specific energy consumption for the different pre-treatments of the raw material ............................................................................................... 18 Chapter 2 Characterization of polyphenols and antioxidant p otenti al of red and white pomace by-product extracts using subcritical water extraction. Figure 1 Schematic diagram of the Pressurized liquid extraction process ................. 51 Figure 2 Correlations between radical scavenging capacity assays (ORAC, FRAP, ABTS and CUPRAC) and t otal flavan-3-ol in grape pomace e xtract by subcritical water extraction ................................................................................. 67Figure 3 Correlations between radical scavenging capacity assays (ORAC, FRAP, ABTS and CUPRAC) and t otal proanthocyanidins (Bate - smith) content in grape pomace extract by subcritical water extraction ........................................ 68 Figure 4 Correlations between radical scavenging capacity assays (ORAC, FRAP, ABTS and CUPRAC) and total anthocyanins in grape pomac e e xtract by subcritical water extraction. ................................................................................ 68 Subcritical water extraction and neoformation of antioxidant compounds from Dunkelfelder grape pomace. Figure 1 Schematic diagram of the Pressurized liquid extraction process ................. 78 Figure 2 Influence of temperature on the polyphenol concentration f or different pressures (25 to 100 bars) and compared with the hydro-alcoholic maceration technique .............................................................................................................. 83Figure 3 Influence of the hydraulic retention time on the polyphenol concentration for differe nt extraction volumes at 150°C temperature, 50 bars hydraulic retention time calculation .................................................................................... 85 Figure 4 Correlations between radical scavenging capacity assays (ORAC, FRAP, ABTS and CUPRAC) and t otal anthocyanins in gr ape pomace extract by subcritical water extraction. ................................................................................ 86 Figure 5 Effect of temperature on the SWE of Flavonol in wet pomace; Procyanidin B1 (A); Catechin (B); Gallic acid (C); Procyanidin C1 (D); and Epicatechin (E). Experiments were conducted in triplicate. Data points shown as the mean value ± standard deviations ........................................................................................... 88 Figure 6 Antioxidant activity measured by the Oxygen Radical Absorbance Capacity (ORAC) essay as a function of SWE process temper ature at 25 bars and compared with the hydro-alcoholic maceration technique ................................. 89Figure 7 Furfural concentration as a function of SWE temperatures (µg/g of DM) with respect to the temperature at 25 bars .......................................................... 89 Chapter3 Selecting ultrafiltration membranes to fractioning high added value compounds from grape pomace extracts. Figure 1 Flow sheet of the experimental apparatus: 1. thermal bath, 2. feed tank, 3. temperature probe, 4. high-pressure pump, 5. security val ve, 6. val ves , 8.

List of Figures pressure probes, 9. membrane cel l system, 11. pres sure control valve, 12. Balance .............................................................................................................. 101 Figure 2 Hydraulic permeability (Lm-2h-1. 10-5Pa) and membrane resistance (Rm) 10 m- 1 to water and contact angle for the ultrafiltration membranes (T = 20 °C)............................................................................................................................. 108Figure 3 Permeate flux during ultrafiltration of grape pomace extract with respect to transmembrane pressure for 11 different membranes; A (VRF=10); B (VRF=2)............................................................................................................................. 111 Figure 4 Evolution of fouling resistance for ultrafiltration membranes tested: GE Osmonics and Alfa Laval membranes. ; A (VRF=10); B (VRF=2). ................. 111 The use of nanofiltration membranes for the fractionation of polyphenols from grape pomace extract Figure 1 Hydraulic permeability Lp for the nanofiltration membranes (T = 20 °C)............................................................................................................................. 137 Figure 2 Evolution of the cumulative permeate volume with processing time for the grape pomace fi ltration experim ents performed with the GE mem brane at a tangential velocity v=2ms-1. ........................................................................... 140Figure 3 Evolution of the permeate flux and volume retention factor with processing time for the grape pomace extract filtration experiments performed with the GE membrane at v=2 ms-1 and T = 20 °C. .......................................................... 141 Figure 4 Evolution of the permeate flux with the volume reduction factor for the experiment GE at 20 105Pa. ............................................................................... 142 Figure 5 Effect of the crossflow velocity on the permeate flux for VRF = 10 with the GE and DK membranes at 20 °C and 3 105Pa. ................................................. 142 Figure 6 Effect of the transmembrane pressur e and MWCO on the steady-state permeate flux for experiments performed at v=2 m s-1 and T = 20 °C. e ..... 143Figure 7 Evolution of fouling resistance for nanofiltration membranes tested:. ; on the steady-state permeate flux for experiments performe d at v=2 m s-1 and T = 20 °C A (Low fouling); B (High fouling) ..................... 145

List of Tables List of Tables : Chapter 1 : Extraction and purification of high added value compounds from by-products of the winemaking chain using alternative/non-conventional processes/technologies. Table 1 Efficiency and operating conditions of PEF-assisted extraction used to extract bioactive compounds from grape by-products ........................................... 9Table 2 Efficiency and operating conditions of HVED-assisted extraction used to extract bioactive compounds from grape by-products ......................................... 13Table 3: Efficiency and operating conditions of US-assisted extraction used to extract bioactive compounds from grape by-products ..................................................... 17Table 4 Advantages and drawbac ks of traditional and alter nativ e pre-treatment techniques ............................................................................................................ 19Table 5 Comparison of li terature works on opti mization of solvent extraction of phenolic constituents from grape by-products (adapted from Spigno et al. 75) ... 23Table 6 Efficie ncy and operating conditions of SWE-assisted extraction used to extract bioactive compounds from grape by-products ......................................... 24Table 7 Efficiency and operating conditions of SFE-assisted extraction used to extract bioactive compounds from grape by-products ..................................................... 28Chapter 2 Characterization of polyphenols and antioxidant p otenti al of red and white pomace by-product extracts using subcritical water extraction. Table 1 Efficiency and operating conditions of SWE-assisted extraction used to extract bioactive compounds from grape by-products ......................................... 47Table 2 Total Phenolics, Total Proanthocyanidins, and Flavan-3-ol Content of the Grape Pomace Sample s (SWE: 100% water, P= 25 bars; Control: 50% ethanol/water 20°C) ............................................................................................. 58 Table 3 Total Anthocyanin Conte nt of the Grape Pomace Sam ples (SWE: 100% water, P= 25 bars; Control: 50% ethanol/water 20°C) ..................................... 63Table 4 Antioxidant Capacity Determined by ABTS, CUPRAC, FRAP, and ORAC Assays for the Grape Pomace Samples ................................................................ 66 Chapter3 Selecting ultrafiltration membranes to fractioning high added value compounds from grape pomace extracts. Table 1: Characteristics of the tested ultrafiltration (UF) membranes (manufacturer data) ................................................................................................................... 102Table 2: Characteristics of the winery pomace extracts used as feed liquids. Values represent mean ± standard deviation (n = 6). ................................................... 107 Table 3: Retention coefficients obtained for several parameters of subcritical grape pomace extracts as a function of different ultrafiltration membranes. .............. 114The use of nanofiltration membranes for the fractionation of polyphenols from grape pomace extract Table 1 Characteristics of tested Nanofiltration (NF) membranes ........................... 132Table 2 Contact angles of tested Nanofiltration (NF) membranes ............................ 134Table 3 Experimental conditions applied in the NF experiments performed and results obtained at VRF=10. ......................................................................................... 141Table 4 Characteristics of the grape pomace extracts used as feed liquids. Values represent mean ± standard deviation (n = 6). ................................................... 146Table 5 Retention coefficients obtained for several parameters of subcritical grape pomace extracts as a function of different nanofiltration membranes) ............. 150

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 1 1. CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION OF HIGH ADDED VALUE COMPOUNDS FROM GRAPE BYPRODUCTS 1.1. INTRODUCTION Throughout the Valuxtract project a book chapter was written "Yammine, S., Ghidossi, R. & Mietton-Peuchot, M., 2014. Extraction and Purification of Phenolic Compounds from By-Products of the Winema king Proces s. In Y. El Rayess, ed. Wine: Phenolic Composition, Classification and Health Benefits. NO VA science publishers, pp. 313- 330 ". In addition with partners of the project a review, which will be presented below, was written to expose all of the publications surrounding this topic. The submitt ed review di splays the main technologies applied or potentially utilizable for the extraction of high added value c ompounds from wine and vine byproducts on the industrial and laboratory scale. With the aim of giving a general introduction of each utilized technology, to all the process parameters and the limits of the t echnology. The ma in approaches such as pressurize d liquid extraction, ultrasound-assisted extraction, microwaves assisted solvent extraction, supercritical or subcritical fluid extraction, pulsed-electric fields (PEF) and high voltage electrical discharges (HVED) are the ma in focus. These technologies are still under development, and so far little or no upsca ling indust rially has been noticed. Consequently, these technologies have been exploited and are one of the most noticed and published topics.

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 2 1.2. EXTRACTION AND PURIFICATION OF HIGH ADDED VALUE COMPOUNDS FROM BY-PRODUCTS OF THE WINEMAKING CHAIN USING ALTERNATIVE/NON-CONVENTIONAL PROCESSES/TECHNOLOGIES Yammine Sami a,b*, Brianceau Sylène c, Manteau Sébastien e, Turk Mohammad c,d, Ghidossi Rémy a,b, Vorobiev Eugène c, Mietton-Peuchot Martine a,b a Université de Brdeaux, Institut des Sciences de la Vigne et du Vin, EA 4577, Unité de recherche oenologie, Villenave d'Ornon, France. b INRA, ISVV, USC 1366 OEnologie, 210 Chemin de Leysotte, CS 50008, F-33882 Villenave d'Ornon, France. c Sorbonne Universités, Université de technologie de Compiègne, EA 4297 TIMR, Centre de recherche Royallieu CS 60 319, 60 203 Compiègne cedex d Ecole Supérieure de Chimie Organique et Minérale, EA 4297 TIMR, Allée du réseau Jean-Marie Buckmaster, 60200 Compiègne, France e SAS SOFRALAB, 79 av. A.A. Thévenet, BP1031-51319 EPERNAY Cedex, France This review has been submitted for the journal of critical reviews in food science and nutrition - accepted in press Abstract Grape byproducts are today consi dered as a cheap source of valuable compounds since existent technologies allow the recovery of target compounds and their recycling. The goal of the current article is to explore the different recovery stages used by both conventiona l and alternative technologies. The intent i s to describe the mechanisms involved by these alternative technologies and to summarize the work done on the improvement of the extraction process of phenolic compounds from winery by-products. With a foc us on the developmental stage of each technology, highlighting the re search need and challenges to be overcome for an industrial implementation of these unitary operations in the overall extraction process. A critical comparison of conventional and alternative techniques is reviewed for the pre-treatment of raw material, the diffusion of polyphenols and the purification of these high added value compounds. This review intends to give the reader some key answers (costs, advantages , drawbacks) to help in t he choice of alternative technologies for extraction purposes. Key words: Ex traction, purification, grape by-products, high added value compounds, non-conventional technologies.

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 3 1.2.1. Introduction The valorization of winery waste products is very promising, since grape is one of the largest produced fruit crops with an annual world production of 58 million tons in 2012.1 About 80 % is used for winemaking and it has been estimated that 13 to 20 % of by-products, which represe nts about 5-8 mi llion tons of potentially exploitable matter, are generated after the winemaking process.2-4 Other estimations report higher value s up to 14.5 mi llion tons solely in E urope.5,6 This represe nts unquestionably an enormous amount of m atter f rom which high added value components could be extracte d. Solid grape w astes are particularly rich in polyphenols, whose use extends to applications in various fields, including cosmetic, nutraceutical, chemical and food industries. Over the last years, polyphenols have attracted a growing interest for t heir potent ial health benefits in preventing heart diseases and cancers.7-10 Their extraction f rom winery waste and their fol lowing purification are of special interest to produce extracts with high added value. Phenolic compounds are usually extracted by classical extraction procedure (Figure 1). The natural vari ability of raw material and the pre-transformation processes (drying, grinding, etc.) could be determi nant for t he quantity and the composition of extract.11 For instance, high temperatures can lead to denaturation of targeted compounds and grinding le ads to a signifi cant i ncrease of unde sired components during extraction. Thus , conventiona l pre-transformation processes decrease the selectivity and/or the efficiency of the extraction process. The selectivity of the extraction processes also depends on the molecular affinity between solvent and solut e during the solid-to-liquid diffusion st ep.12 However, toxicity, environmental safety, and financial feasibility should als o be considered in the selection of a solvent for the extraction of high added value compound. Towards the end of the process, a purification step may be required to obtain extracts with high purity of phenolic compounds. Resin adsorption is comm only used at indust rial scale.13,14 The major draw back of this te chnique is the use of a large amount of solvent noticeably during polyphenols desorption, which need to be further evaporated.

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 4 Figure 1: Conventional extraction procedure for the recovery of high added value components from grape wastes Losses of some compounds, l ow production efficiency, ti me- and energy-consuming procedures (prolonged heating and stirring, use of large volumes of solvent...) may be encountered using this conventional extraction procedure. Recent trends in extract ion techni ques have largely focused on findi ng solutions that minimize the use of solvent and energy. For these purposes, alternative techniques have been deeply studied to enhance the overall yields in phenolic compounds and to decrease the operational costs of the process. These techniques include: - Alternative pre-treatments techniques: ultrasounds, pulsed electric fields and high voltage discharges, - Non-conventional solvent extraction under high pressure: supercritical fluid extraction and subcritical water extraction and, - Alternative purification technologies, such as membrane processing. Although lots of experimental studies particularly focused on improving the overall extraction process from solid winery by-products, none of these alternative technologies are currently used at i ndustrial sca le for this applica tion. This pape r intends to describe the mechanisms involved by these alternative technologies and to summarize the work done on the improvement of the extraction process of phenolic compounds from winery by-products. In this review, the contribution focuses on the developmental stage of e ach tec hnology, highlighting the re search need and

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 5 challenges to be overcome for an indus trial i mplement ation of these unita ry operations in the overall extraction process. A critical comparison of conventional and alternative techniques will be described for the pre-treatment of raw material, the diffusion of polyphenols and the purification of these high added value compounds. This review inte nds to give the reader some key answers (cos ts, advant ages, drawbacks) to help him in t he choice of alternat ive technologie s for extraction purposes. 1.2.2. Pre-treatment of grape by-products for the enhancement of mass transfer phenomena: conventional and alternative techniques Phenolic compounds exist in plants enclosed in particular structures such as the vacuoles of plant cells and lipoprot eins bilayers.15 In int act cells, the membra ne envelope restricts the exchange between the intracellular media and the surrounding solvent. Consequently, conventional solvent extraction techniques such as maceration or diffusion require long extraction time, due to the slow diffusion of solvent and solute through the solid. 16 Thus, the degrada tion of cel l-wall and of intracel lular components is a fundamental step to improve the release of these compounds from the grape tissues. Extraction processes can be enhanced by several pre-treatments of the plant materials that are able to physically damage the cells, such as: grinding, pulsed electric field, high voltage electric discharges and ultrasound. 1.2.2.1. Grinding Grinding is the most conventional pre-treatment technique and is currently used in the extraction industry to shorten the time of diffusion and enhance the yield of targeted bio-compounds. The mechanical action induced by grinding leads to an increase of the exchange surface. However, grinding also leads to the overheating of the plant matrix. Two phenomena are responsible of this released heat: - Release of energy caused by the fracturing of the matrix, - Release of energy due to overgrinding of the matrix.17 Phenolic compounds, and noticeably anthocyanins, are particularly thermosensitive and can be degraded or lose their functionality.18

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 6 On the ot her hand, the t ype of plant m atrix, and particularly its moisture content, affects the electrical energy requirement, the specific energy consumption and the equipment to be used.19 Two types of grinding processes can be used in the food industry: dry and wet grinding. A previ ous study demons trated that spec ific energy consumption varied between 420 and 800 kJ/kg of raw rice using dry grinding, while about 14,000 kJ/kg were required in the case of wet grinding (water-to-rice ratio = 2).20 Consequently, a preliminary drying step, which is associated with matrix heating, is often required to facilitate the grinding and reduce its associated cost.20,21 Finally, increased difficulties during the filtration and purification steps due to small particles in s uspension in the solvent are another l imitat ion for the use of grinding in the extraction manufactories. Emerging technologies for the physical alteration of raw material (i.e. pulsed electric fields, high voltage electric discharges and ultrasounds) are based on non-thermal concepts. These three technologies can physically affect the permeability of the cell by different mechanisms.22-25 1.2.2.2. Pulsed electrical field (PEF) assisted extraction Electroporation phenomena: When subjected to an external electric field, the charge accumulat ion on the membrane surfaces induces the inc rease of transmembrane potential of the cell membrane, initiating pore formation.26 Typically, electroporation phenomena requires some threshold value of transmembrane potential around 0.5 - 1.5 V.27 Above the crit ical value of transmembrane potential, the expansion of pores present in weak areas of the membrane will induce drastic increase of permeability 28,29 and will facilitate the leakage of intracellular compounds.30,31 Thus, Pulsed E lectric Field (PE F) treatment increases transmembrane transport of molecules.31,32 For cell ular tissues of 60-120 µm in dia meter, i nitiation of pore formation can be achieved us ing electr ic field s trengths of 0.1 - 0.5 kV/cm and treatment times of very short duration (within 10-4 - 10-2 s)33 without any significant temperature increase.34,35 Pulsed electric field pre-treatment of winery by-products: PEF treatment prior to conventional extraction allowed a better recovery of phenolic compounds from different winery by-products (Table 1). In most of these studies, the raw materials were submerged into water in order to improve electrical contacts between electrodes.

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 7 Treatment with liquid-to-solid ratio above 5 required high electric field strength (i.e. E > 13 kV/cm) to be effective for the enhancement of polyphenols extraction. As a consequence, specific energy cons umptions were relatively high (i.e. 272 < W < 762 kJ/kg of treated raw material). On the contrary, pre-treatment by PEF combined with an accurate densification of wet pomace or wet skins can be achieved at lower electric field strengths (i.e. E ≈ 1.2 kV/cm) and lower energy requirements (i.e. 18 < W < 30 kJ/kg of treat ed raw m aterial). The treatment of compacte d wet winery by-products requires less output current, which can be advantageous for the industrial implementation of PEF.36 Pulse forms used we re of different s hape (monopolar, bipolar or exponential). However, no comparison of the effect of pulse shape on the extractability of phenolic bio-components is available in the existing literature. Interestingly, a previous study showed that PEF treatment causes irreversible perforations in the cell wall of the outer hypodermis and distention of the fiber cell wall polysaccharides at the inner hypodermis.37 This electroporati on phenomenon may allow the specific recovery of anthocyanins that are particularly located in the upper cell layers of the hypodermis. For instance, High Intensity Pulsed Electrical Field (Hi-PEF) treatment of fermented grape pomace (13.3 kV/cm, W = 272 kJ/kg) allowed the selective recovery of anthocyanins and the production of extracts with a high ratio anthocyanins/Total Phenolic Compounds (TPC). This reflects an increase of 40 % tha t cannot be achi eved by conventional e xtraction procedure, such as grinding combined t o diffusion (ratio anthocyanins/T PC < 5 %).38 Moderate PEF treatments (E < 3.0 kV/cm, W < 20 kJ/kg) were al so effective in enhancing anthocyanins extraction from grape skins (+ 17 %)39 and grape pomace (+ 19 %)36. Consequently, PEF can replace conventional pre-treatments of grape by-products (e.g. dehydration and grinding), which ha ve impa cts on product qua lity and are more energy consuming, with the combined objectives of cost reduction and selectivity of extraction. Scale-up of the technology/Stage of development: Based on existing concepts, and noticeably on sucrose extraction from sugar beets at industrial scale 25,40,41, the pre-treatment of grape by-products by PEF should be feasible at larger scale (pilot and industrial scale). Progress in the development of continuous flow treatment chambers for PEF processing have allowed the treatment of material that cannot be pumped

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 8 (solid products) using belt or rotating systems.42 Moreover, some recent developments of pulsed power systems, which are usable for continuous delivery of high amounts of electrical energy and high electric fiel d strengths a nd suitabl e for food industry applications, have allowed the scale-up of the technology.25 Research needs and challenges: While electroporation devices for minimally processed fruits and vegetables are already in operation43, the electroporation devices for extra ction of valuable components from grape by-products still requi re some research and development prior to any reliable operation in an industrial environment. At the microscopic scale, questions still remain regarding the effect of electric pulses on the cell structure of the plant material and on the targeted bio-components. For insta nce, it was demonstrated tha t PEF trea tment can modif y molecular interactions between intracellular c omponents37 and induce a rupture of polymer chains (decondensation of the tannins).44 Further studies might be of importance to evaluate the effect of PEF treatment on the properties of the targeted molecul e (bioavailability, functionality, taste...) before using these extracts in food, oenological or nutraceutical applications. In order to imple ment t he PEF processing step into exist ing processes in a distillery, a winery or an extracts manufactory, a systemic/integrative approach will be required considering the diversity of raw material to be treated (i.e. pomace, skins, stems, seeds and vine shoots): - Depending on the grape by-product to be treated, the peak voltage required, the peak current (which depends on product conductivity, on the minimum treatment chamber cross section and on the electrical resistance of the chamber), the average power (dependent on the processing capacity (kg or tons /hour...)) and on the pulse waveform (exponential decay or rectangular pulses) can vary subs tantially, which renders the design of a power supply for multiple applications challenging. - The suitabil ity of the treatment chamber may be affec ted by the raw materials to be treated, most noticeably the materials' pumpability that is critical for a continuous treatment at an industrial scale.

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 9 Grape by-product matrix Operating conditions Extraction conditions Targeted bio-compounds (Relative increase) Red grape pomace (Dornfelder)39 30 exponential pulses in water 3 kV/cm, 10 kJ/kg Total treatment time : 15 sec 1h at 70°C in ethanol/water (50:50, v/v) Anthocyanins (1.17) * Polyphenols (1.59) * White grape skins (Chardonnay)45 100 bipolar pulses of rectangular shape without addition of conductive liquid 1.3 kV/cm, 30 kJ/kg Effective treatment time: 100 ms at 20°C 3h at 20°C in water Polyphenols (1.12) * Grape seeds (Pinot Meunier)46 600 exponential pulses in water (L/S ratio: 5) 20 kV/cm, 320 kJ/kg Effective treatment time: 6 ms at 50°C 1h at 50°C in ethanol/water (30:70, v/v) Polyphenols (1.30) * Reduction of diffusion time by 2 Fermented grape pomace (Dunkelfelder)36 1700 monopolar pulses of rectangular shape without addition of conductive liquid 1.2 kV/cm, 18 kJ/kg Effective treatment time: 170 ms at 20°C 7h at 20°C in ethanol/water (50:50, v/v) Anthocyanins (1.19) * Polyphenols (1.13) * Vine shoots (Grenache blanc)47 1500 exponential pulses in water (L/S ratio: 20) 13.0 kV/cm, 762 kJ/kg Effective treatment time: 15 ms at 50°C 4h at 50°C in 0.1 M of NaOH in water Polyphenols (2.09) * Kaempferol: 0.156 mg/g Epicatechin: 1.747 mg/g Resveratrol: 0.032 mg/g Fermented grape pomace (Dunkelfelder)38 750 exponential pulses in water (L/S ratio: 10) 13.0 kV/cm, 272 kJ/kg Effective treatment time: 7,5 ms at 25°C Without diffusion Anthocyanins (5.3)** Polyphenols (0.47)** Table 1: Efficiency and operating conditions of PEF-assisted extraction used to extract bioactive compounds from grape by-products * In comparison with control extraction, performed in the same conditions but without PEF pre-treatment ** In comparison with control extraction of grinded pomace in water (2h - 20°C under stirring)

CHAPTER 1: STATE OF THE ART ALTERNATIVE PROCESS OF EXTRACTION AND PURIFICATION 10 1.2.2.3. High voltage electr ical disc harges (HVED) assisted extraction Principles and mechanisms: The first step of HVED is the formation and the propagation of a streamer, which is composed of thin ionized vapor channels, from a needle electrode (pre-breakdown phase). The second phase occurs when the streamer reaches the plate electrode (breakdown phase). These two phases are accompanied by different secondary phenomena such as propagation of pressure shock waves in the surrounding media, emis sion of UV light, gas bubbles c avitati on and chemica l reactions generating reactive species.22,48,49 At the macroscopic level, the application of electrical discharges on different wine by-products (grape seeds, grape pomace...) results on the fragmentation of the particles.50 Depending on the matrix and after effective discharge treatment, the size reduction of the particles treated by electrical discharge is rather similar to that obtained after grinding the product.51 HVED-assisted extraction of valuable bio-compounds from winery by-products: Electrical discharges have been successfully applied at both laboratory (1 L) and pilot (35 L) sca les, in batch, for the enhanceme nt of pol yphenols extraction f rom winemaking by-products (Table 2). At the macroscopic level, the treated grape by-products were clearly fragmented after the application of electrical discharges. The increase of the exchange surfa ce promote s the relea se of non-cell-wall phenolic components and enhances the ethanol transport into cells leading to an increase of phenolic compounds recovery.52,53 Moreover, the highly turbulent conditions induced by HV ED accelerate t he convection of these components from particl es to the surrounding medium. In general, specific energy consumption ranged from 32 kJ/kg and 254 kJ/kg of treated raw material to achieve i nteresting enhancement of phenolic c ompounds extraction. At laboratory scale, lignocellulosic biomass (i.e. grape stems, vine shoots) required the highest energy input (> 190 kJ/kg), probably because these biomasses are more resistant to electric discharges than grape skins or seeds. However, the choice of effective HVED treatment time should be accurately evaluaquotesdbs_dbs47.pdfusesText_47

[PDF] Maths dm pour demain

[PDF] Maths dm rentree

[PDF] Maths dm repère orthonormé

[PDF] maths dm sil vous plait pour jeudi 13 décembre j'ai du mal a le faire j'ai vraiment besoin d'aide

[PDF] Maths dm somme

[PDF] maths dm sur le calcul

[PDF] maths dm sur les fonctions

[PDF] Maths dm sur les racines carrés

[PDF] maths dm trajet

[PDF] MATHS DM URGENT

[PDF] Maths du niveau quatrième

[PDF] maths ecriture scientifique help

[PDF] maths ecs exercices corrigés

[PDF] Maths effectifs

[PDF] Maths égalité de 2 carrés